R-phenylacetylcarbinol (R-PAC) is a precursor for the chemical synthesis of ephedrine and pseudoephedrine. A method for the production of R-PAC by fermenting yeast (Saccharomyces cerevisiae) in the presence of benzaldehyde and molasses was established in the last century already (Hildebrandt & Klavehn 1932, DE-PS 548 459).
It also known for quite some time that the catalyst responsible for the synthesis of R-PAC in micro-organisms is the enzyme pyruvate decarboxylase (PDC). The enzyme converts the stereo-selective carboligation of a C2 moiety stemming from pyruvic acid and benzaldehyde. The catalyst also performs the carboligation of a number of other carbonyl-compound. With certain enzymes e.g. from Zymomonas mobilis also acetaldehyde instead of pyruvic acid can be used as substrate for the process.
Pyruvate decarboxylase (PDC) was identified and characterised in different organisms besides Saccharomyces cerevisiae and Zymomonas mobilis. The enzymatic synthesis of R-phenylacetylcarbinol by PDC has been described so far only in an aqueous one-phase-system. There is no information that pyruvate decarboxylase is also active in an organic solvent or in an emulsion of organic solvents and water.
In WO 96/37620 a process for producing acyloins, especially R-phenylacetylcarbinol from benzaldehyde and acetaldehyde or pyruvate in presence of pyruvate decarboxylase from Zymomonas mobilis is disclosed.